Answer:
The writer adds brackets to the sample sentence because Brackets allow the writer to change the verb tense of "add" so that it is consistent with the other verb tense in the sentence.
Explanation:
Whenever someone is making a quotation in a written work and the tense of the quotation doesn't match the syntaxis of the rest of the writing, it can be modified with the implementation of brackets around it or a specific part of it as we see in this line the word added has the brackets around (ed) that is the part that changes in past conjugation.
